The general objective of the proposed research is an understanding of the biology of group A streptococci and other groups of streptococci and the relationship of the former to acute rheumatic fever and acute nephritis. Although considerable progress has been made in our understanding of the various components and products of this group of organisms, many gaps remain and we are still uncertain of the mechanisms by which these organisms result in these serious non-suppurative complications and of ways to improve our imperfect approaches to the control of these diseases. The specific aims are as follows: 1) identification, characterization and separation of streptococcal components and products; 2) elucidation of the influence of temperate and virulent bacteriophages and phage-associated lysins on the formation and release of streptococcal products; 3) examination of the possible role of well- defined streptococcal antigens and streptococcal antigen-antibody complexes in pathologic processes and in the pathogenesis of renal and heart disease.